<?php

/**
 * @file
 * Classes used for updating various files in the Drupal webroot. These
 * classes use a FileTransfer object to actually perform the operations.
 * Normally, the FileTransfer is provided when the site owner is redirected to
 * authorize.php as part of a multistep process.
 */

/**
 * Interface for a class which can update a Drupal project.
 *
 * An Updater currently serves the following purposes:
 *   - It can take a given directory, and determine if it can operate on it.
 *   - It can move the contents of that directory into the appropriate place
 *     on the system using FileTransfer classes.
 *   - It can return a list of "next steps" after an update or install.
 *   - In the future, it will most likely perform some of those steps as well.
 */
interface DrupalUpdaterInterface {

	/**
	 * Checks if the project is installed.
	 *
	 * @return bool
	 */
	public function isInstalled();

	/**
	 * Returns the system name of the project.
	 *
	 * @param string $directory
	 *  A directory containing a project.
	 */
	public static function getProjectName($directory);

	/**
	 * @return string
	 *   An absolute path to the default install location.
	 */
	public function getInstallDirectory();

	/**
	 * Determine if the Updater can handle the project provided in $directory.
	 *
	 * @todo: Provide something more rational here, like a project spec file.
	 *
	 * @param string $directory
	 *
	 * @return bool
	 *   TRUE if the project is installed, FALSE if not.
	 */
	public static function canUpdateDirectory($directory);

	/**
	 * Actions to run after an install has occurred.
	 */
	public function postInstall();

	/**
	 * Actions to run after an update has occurred.
	 */
	public function postUpdate();
}

/**
 * Base class for Updaters used in Drupal.
 */
class Updater {

	/**
	 * @var string $source Directory to install from.
	 */
	public $source;

	public function __construct($source) {
		$this->source = $source;
		$this->name = self::getProjectName($source);
		$this->title = self::getProjectTitle($source);
	}

	/**
	 * Return an Updater of the appropriate type depending on the source.
	 *
	 * If a directory is provided which contains a module, will return a
	 * ModuleUpdater.
	 *
	 * @param string $source
	 *   Directory of a Drupal project.
	 *
	 * @return Updater
	 */
	public static function factory($source) {
		if (is_dir($source)) {
			$updater = self::getUpdaterFromDirectory($source);
		}
		else {
			throw new UpdaterException(t('Unable to determine the type of the source directory.'));
		}
		return new $updater($source);
	}

	/**
	 * Determine which Updater class can operate on the given directory.
	 *
	 * @param string $directory
	 *   Extracted Drupal project.
	 *
	 * @return string
	 *   The class name which can work with this project type.
	 */
	public static function getUpdaterFromDirectory($directory) {
		// Gets a list of possible implementing classes.
		$updaters = drupal_get_updaters();
		foreach ($updaters as $updater) {
			$class = $updater['class'];
			if (call_user_func(array($class, 'canUpdateDirectory'), $directory)) {
				return $class;
			}
		}
		throw new UpdaterException(t('Cannot determine the type of project.'));
	}

	/**
	 * Figure out what the most important (or only) info file is in a directory.
	 *
	 * Since there is no enforcement of which info file is the project's "main"
	 * info file, this will get one with the same name as the directory, or the
	 * first one it finds.  Not ideal, but needs a larger solution.
	 *
	 * @param string $directory
	 *   Directory to search in.
	 *
	 * @return string
	 *   Path to the info file.
	 */
	public static function findInfoFile($directory) {
		$info_files = file_scan_directory($directory, '/.*\.info$/');
		if (!$info_files) {
			return FALSE;
		}
		foreach ($info_files as $info_file) {
			if (drupal_substr($info_file->filename, 0, -5) == drupal_basename($directory)) {
				// Info file Has the same name as the directory, return it.
				return $info_file->uri;
			}
		}
		// Otherwise, return the first one.
		$info_file = array_shift($info_files);
		return $info_file->uri;
	}

	/**
	 * Get the name of the project directory (basename).
	 *
	 * @todo: It would be nice, if projects contained an info file which could
	 *        provide their canonical name.
	 *
	 * @param string $directory
	 *
	 * @return string
	 *   The name of the project.
	 */
	public static function getProjectName($directory) {
		return drupal_basename($directory);
	}

	/**
	 * Return the project name from a Drupal info file.
	 *
	 * @param string $directory
	 *   Directory to search for the info file.
	 *
	 * @return string
	 *   The title of the project.
	 */
	public static function getProjectTitle($directory) {
		$info_file = self::findInfoFile($directory);
		$info = drupal_parse_info_file($info_file);
		if (empty($info)) {
			throw new UpdaterException(t('Unable to parse info file: %info_file.', array('%info_file' => $info_file)));
		}
		if (empty($info['name'])) {
			throw new UpdaterException(t("The info file (%info_file) does not define a 'name' attribute.", array('%info_file' => $info_file)));
		}
		return $info['name'];
	}

	/**
	 * Store the default parameters for the Updater.
	 *
	 * @param array $overrides
	 *   An array of overrides for the default parameters.
	 *
	 * @return array
	 *   An array of configuration parameters for an update or install operation.
	 */
	protected function getInstallArgs($overrides = array()) {
		$args = array(
				'make_backup' => FALSE,
				'install_dir' => $this->getInstallDirectory(),
				'backup_dir'  => $this->getBackupDir(),
		);
		return array_merge($args, $overrides);
	}

	/**
	 * Updates a Drupal project, returns a list of next actions.
	 *
	 * @param FileTransfer $filetransfer
	 *   Object that is a child of FileTransfer. Used for moving files
	 *   to the server.
	 * @param array $overrides
	 *   An array of settings to override defaults; see self::getInstallArgs().
	 *
	 * @return array
	 *   An array of links which the user may need to complete the update
	 */
	public function update(&$filetransfer, $overrides = array()) {
		try {
			// Establish arguments with possible overrides.
			$args = $this->getInstallArgs($overrides);

			// Take a Backup.
			if ($args['make_backup']) {
				$this->makeBackup($args['install_dir'], $args['backup_dir']);
			}

			if (!$this->name) {
				// This is bad, don't want to delete the install directory.
				throw new UpdaterException(t('Fatal error in update, cowardly refusing to wipe out the install directory.'));
			}

			// Make sure the installation parent directory exists and is writable.
			$this->prepareInstallDirectory($filetransfer, $args['install_dir']);

			// Note: If the project is installed in sites/all, it will not be
			// deleted. It will be installed in sites/default as that will override
			// the sites/all reference and not break other sites which are using it.
			if (is_dir($args['install_dir'] . '/' . $this->name)) {
				// Remove the existing installed file.
				$filetransfer->removeDirectory($args['install_dir'] . '/' . $this->name);
			}

			// Copy the directory in place.
			$filetransfer->copyDirectory($this->source, $args['install_dir']);

			// Make sure what we just installed is readable by the web server.
			$this->makeWorldReadable($filetransfer, $args['install_dir'] . '/' . $this->name);

			// Run the updates.
			// @TODO: decide if we want to implement this.
			$this->postUpdate();

			// For now, just return a list of links of things to do.
			return $this->postUpdateTasks();
		}
		catch (FileTransferException $e) {
			throw new UpdaterFileTransferException(t('File Transfer failed, reason: !reason', array('!reason' => strtr($e->getMessage(), $e->arguments))));
		}
	}

	/**
	 * Installs a Drupal project, returns a list of next actions.
	 *
	 * @param FileTransfer $filetransfer
	 *   Object that is a child of FileTransfer.
	 * @param array $overrides
	 *   An array of settings to override defaults; see self::getInstallArgs().
	 *
	 * @return array
	 *   An array of links which the user may need to complete the install.
	 */
	public function install(&$filetransfer, $overrides = array()) {
		try {
			// Establish arguments with possible overrides.
			$args = $this->getInstallArgs($overrides);

			// Make sure the installation parent directory exists and is writable.
			$this->prepareInstallDirectory($filetransfer, $args['install_dir']);

			// Copy the directory in place.
			$filetransfer->copyDirectory($this->source, $args['install_dir']);

			// Make sure what we just installed is readable by the web server.
			$this->makeWorldReadable($filetransfer, $args['install_dir'] . '/' . $this->name);

			// Potentially enable something?
			// @TODO: decide if we want to implement this.
			$this->postInstall();
			// For now, just return a list of links of things to do.
			return $this->postInstallTasks();
		}
		catch (FileTransferException $e) {
			throw new UpdaterFileTransferException(t('File Transfer failed, reason: !reason', array('!reason' => strtr($e->getMessage(), $e->arguments))));
		}
	}

	/**
	 * Make sure the installation parent directory exists and is writable.
	 *
	 * @param FileTransfer $filetransfer
	 *   Object which is a child of FileTransfer.
	 * @param string $directory
	 *   The installation directory to prepare.
	 */
	public function prepareInstallDirectory(&$filetransfer, $directory) {
		// Make the parent dir writable if need be and create the dir.
		if (!is_dir($directory)) {
			$parent_dir = dirname($directory);
			if (!is_writable($parent_dir)) {
				@chmod($parent_dir, 0755);
				// It is expected that this will fail if the directory is owned by the
				// FTP user. If the FTP user == web server, it will succeed.
				try {
					$filetransfer->createDirectory($directory);
					$this->makeWorldReadable($filetransfer, $directory);
				}
				catch (FileTransferException $e) {
					// Probably still not writable. Try to chmod and do it again.
					// @todo: Make a new exception class so we can catch it differently.
					try {
						$old_perms = substr(sprintf('%o', fileperms($parent_dir)), -4);
						$filetransfer->chmod($parent_dir, 0755);
						$filetransfer->createDirectory($directory);
						$this->makeWorldReadable($filetransfer, $directory);
						// Put the permissions back.
						$filetransfer->chmod($parent_dir, intval($old_perms, 8));
					}
					catch (FileTransferException $e) {
						$message = t($e->getMessage(), $e->arguments);
						$throw_message = t('Unable to create %directory due to the following: %reason', array('%directory' => $install_location, '%reason' => $message));
						throw new UpdaterException($throw_message);
					}
				}
				// Put the parent directory back.
				@chmod($parent_dir, 0555);
			}
		}
	}

	/**
	 * Ensure that a given directory is world readable.
	 *
	 * @param FileTransfer $filetransfer
	 *   Object which is a child of FileTransfer.
	 * @param string $path
	 *   The file path to make world readable.
	 * @param bool $recursive
	 *   If the chmod should be applied recursively.
	 */
	public function makeWorldReadable(&$filetransfer, $path, $recursive = TRUE) {
		if (!is_executable($path)) {
			// Set it to read + execute.
			$new_perms = substr(sprintf('%o', fileperms($path)), -4, -1) . "5";
			$filetransfer->chmod($path, intval($new_perms, 8), $recursive);
		}
	}

	/**
	 * Perform a backup.
	 *
	 * @todo Not implemented.
	 */
	public function makeBackup(&$filetransfer, $from, $to) {
	}

	/**
	 * Return the full path to a directory where backups should be written.
	 */
	public function getBackupDir() {
		return file_stream_wrapper_get_instance_by_scheme('temporary')->getDirectoryPath();
	}

	/**
	 * Perform actions after new code is updated.
	 */
	public function postUpdate() {
	}

	/**
	 * Perform actions after installation.
	 */
	public function postInstall() {
	}

	/**
	 * Return an array of links to pages that should be visited post operation.
	 *
	 * @return array
	 *   Links which provide actions to take after the install is finished.
	 */
	public function postInstallTasks() {
		return array();
	}

	/**
	 * Return an array of links to pages that should be visited post operation.
	 *
	 * @return array
	 *   Links which provide actions to take after the update is finished.
	 */
	public function postUpdateTasks() {
		return array();
	}
}

/**
 * Exception class for the Updater class hierarchy.
 *
 * This is identical to the base Exception class, we just give it a more
 * specific name so that call sites that want to tell the difference can
 * specifically catch these exceptions and treat them differently.
 */
class UpdaterException extends Exception {
}

/**
 * Child class of UpdaterException that indicates a FileTransfer exception.
 *
 * We have to catch FileTransfer exceptions and wrap those in t(), since
 * FileTransfer is so low-level that it doesn't use any Drupal APIs and none
 * of the strings are translated.
 */
class UpdaterFileTransferException extends UpdaterException {
}
